Celebs are speaking out following the comments by former "Growing Pains" heartthrob Kirk Cameron about homosexuality and gay marriage.

Cameron, who is an active advocate for conservative Christian values, said Friday on CNN's "Piers Morgan Tonight" that his beliefs don't allow him to support gay marriage. "Marriage is almost as old as dirt, and it was defined in the garden between Adam and Eve. One man, one woman for life till death do you part. So do I support the idea of gay marriage? No, I don't."

In his interview with Morgan, Cameron also called homosexuality "unnatural" and said he believes it can lead to a destruction of society. "It's detrimental and ultimately destructive to so many of the foundations of civilization," he said.

Among the stars to criticize Cameron's words on Twitter were some former "Growing Pains" co-stars including Alan Thicke: "I'm getting him some new books. The Old Testament simply can't be expected to explain everything." "Growing Pains" star Tracey Gold said, "I am a strong supporter of the #LGBT Community, and I believe in equal rights for all. #NOH8 #LOVE."

"Modern Family" star Jesse Tyler Ferguson commented, "The only unnatural thing about me being gay is that I had a crush on Kirk Cameron until about 24 hours ago." "Raising Hope" star Martha Plimpton said, "The word "Equality" shows up too much in our founding documents for anyone to pretend it's not the American way. #usethe19th #equalitynow."

"Will & Grace" and "Smash" star Debra Messing posted, "i want to thank Piers Morgan for his response to what he wud say to HIS child if (s)he came out: 'Great, as long as you're happy.'" "The Late Late Show" host Craig Ferguson said, "Kirk Cameron makes me ashamed to be a failed actor. We don't all think like that NoH8."

The Gay & Lesbian Alliance Against Defamation (GLAAD) also expressed concern. "Cameron has the right to share his views, but as a result of GLAAD's work, people of faith who support LGBT people are making sure their voices are louder," said spokesman Herndon Graddick. "Thousands, including many people of faith, have shared the campaign and spoken out against Cameron's remarks."

"In this interview, Kirk Cameron sounds even more dated than his 1980s TV character," Graddick added. "Cameron is out of step with a growing majority of Americans, particularly people of faith who believe that their gay and lesbian brothers and sisters should be loved and accepted based on their character and not condemned because of their sexual orientation."